1. Field of the Invention
This invention relates generally to roll forming of sheet materials to form members and, more particularly, to types of members that may be formed from, a process for, and tooling to perform, the non-stretch bending of sheets of material, simultaneously in a plurality of directions, thus yielding a product that has cyclically variable cross-sections.
2. Description of Related Art
Many manufacturing processes and machines are known for forming structural and other members to be used in connecting various elements and assembling or constructing various structures. Among these known means are corrugated panels, which enjoy world-wide popularity as a simple, low cost way of providing thin sheet stock material with greatly increased stiffness. Consequently, corrugated structures enjoy world-wide popularity for a wide variety of applications.
Corrugated panels are commonly supported by a network of support beams, which typically are elongated, constant cross-section members. The designer is faced with certain interface difficulties where adjoining non-planar corrugated panels meet, and where corrugated panels meet their linear support beams. These difficulties include:
Joining non-planar corrugated panels presents both load transfer and environmental closure problems. PA1 Gaps between a corrugated panel and its support beam, occurring at each cycle of the corrugation pattern, often need closure to block against foreign matter entry. PA1 Load transfer between a corrugated panel and its support beam often places constraints on panel design where the transverse shear stress must be redistributed to transfer its shear load to the beam at the corrugation apex points in contact with it.
Solutions to these problems are known. Block cross-section filler material is used to fill voids. Constant cross-section edge members have been designed to provide an acceptable interface structure between non-planar panels and between corrugated panels and their linear support elements.
A widely used means of making long, constant cross-section edge members is roll forming. The roll forming process uses the simple technique of bending sheet stock without the need for in-plane straining or stretching used for more complex, costly processes, such as stretch forming or pressing. Thus, the roll forming process requires minimal forming forces and material ductility, and enjoys wide use in fabricating many low cost linear products.
The known means for roll forming shaped members generally uses a plurality of serially positioned axisymmetric roller sets to form a predetermined constant cross-section linear member from a supply of continuous flat metal sheet stock fed into the machine. Drives and guides provide means to ensure the proper course of the material through the machine. Each roller set consists of at least two mated rollers, which are axisymmetrical, body-of-revolution rollers, designed to work in concert to incrementally bend the entering sheet stock material toward the finally desired shape. Each forming step in the machine is limited to the degree permitted by the supply material constraints of strength, stiffness and ductility.
Over the past several decades, roll forming tools have been highly developed to provide many sophisticated adaptations to improve formability, forming speeds and shape complexities. However, these known roll forming tools and machines are still characterized and limited by the fundamental properties of serially positioned, axisymmetric roller sets, acting upon a supply of flat sheet stock, to form a desired constant cross-section product by bending.
Many other classes of machines and processes are also known for forming complex shaped products, but these machines and processes form such products by stretch and/or shear forming the materials used, requiring much greater forming forces and material ductility, resulting in higher costs compared to those formed by simple bending processes.
The following listed U.S. Patents disclose various members formed by, or methods and apparatus for roll or stretch forming sheets of material into various shaped members: U.S. Pat. Nos. 317,868, 899,817, 1,677,031, 2,007,284, 2,251,967, 2,294,324, 2,471,490, 2,505,241, 2,664,177, 2,781,877, 3,137,922, 3,344,641, 3,462,989, 3,992,162, 4,220,423, 4,526,024, 4,578,978, 4,662,734 and 4,876,837. However, the specific disclosures of these patents fail to show or utilize apparatus, and/or processes to design tooling, or to form complex members by the non-stretch bending of sheet materials, in a plurality of directions, using serial sets of non-axisymmetrical rollers, as disclosed and claimed by applicant herein. Applicant's present invention is applicable throughout the world, and should increase the use and decrease the cost of corrugated constructions for varied uses and applications.